Motor with control device and heat sink and intermediate thermal insulation layer in-between

ABSTRACT

A motor system includes a stator, a rotor, a number of power modules which each have planar contact faces for dissipating heat, a control device which is designed to actuate the power modules, a housing, wherein the stator and the rotor are arranged inside the housing, and at least one heat sink. The heat sink has a number of planar contact faces which are connected in a thermally conductive fashion to respectively corresponding contact faces of the power modules. The heat sink has regions for dissipating heat, wherein a coolant flows around the regions in order to dissipate heat.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a motor system.

The invention is based on the object of making available a motor systemwith thermal properties which are optimized in comparison with the priorart.

The invention solves this problem by a motor system having a stator, arotor, a number of power modules which each have planar contact facesfor dissipating heat, a control device which is designed to actuate thepower modules, a housing, wherein the stator and the rotor are arrangedinside the housing, and at least one heat sink. The heat sink has anumber of planar contact faces which are connected in a thermallyconductive fashion to respectively corresponding contact faces of thepower modules. The heat sink has regions for dissipating heat, wherein acoolant flows around the regions in order to dissipate heat.

Firstly, the motor system has a stator, a rotor and typically also amotor shaft. The motor shaft is coupled in a mechanically rotationallyfixed fashion to the rotor. The motor shaft defines a radial directionand an axial direction of the motor system. The axial direction is thatdirection in which the rotational axis of the motor shaft extends, andthe radial direction is the direction radially with respect to therotational axis of the motor shaft.

The stator can conventionally serve to generate a rotating magneticfield. The stator can have stator poles which are provided withindividual windings. The stator and rotor are referred to in combinationas an active part.

The motor system also has a number, for example between 2 and 20, ofpower modules which each have planar contact faces for dissipating heat.The power modules can be, for example, IGBT modules. The power modulescan have power semiconductors which generate heat during theiroperation. In this respect, reference is also made to the relevantspecialist literature.

The motor system also has a control device, for example in the form of amicrocontroller, of a DSP or of an FPGA. The control device is designedto actuate the power modules, for example actuate them in such a waythat suitable actuation voltages and/or suitable actuation currents aregenerated for one or more windings of the stator and/or one or morewindings of the rotor. The control device can provide the function of afrequency inverter in conjunction with the power modules (and furthercomponents).

The motor system also has a housing, wherein the stator and the rotorare arranged inside the housing.

The motor system also has at least one heat sink. The heat sink has anumber of planar, in particular rectangular, contact faces which areconnected, in particular directly, in a thermally conductive fashion torespectively corresponding contact faces of the power modules. Thenumber of contact faces is, in particular, identical to the number ofpower modules. The heat sink has regions for dissipating heat to acoolant, for example air, wherein the coolant flows around the regionsin order to dissipate heat. The coolant preferably flows through thehousing in the axial direction.

The assembly composed of power modules and heat sinks as well as thecontrol device can also be arranged inside the housing.

The at least one heat sink can be embodied (provided, manufactured)separately from the housing, wherein the heat sink can be mechanicallycoupled, for example screwed, to the housing. The heat sink thereforeforms an inlay heat sink. The motor system can further have end-sideterminating pieces, for example in the form of an A end plate and of a Bend plate. For this case, the at least one heat sink can be embodied(provided, manufactured) separately from the housing, wherein the heatsink can then be mechanically coupled, for example screwed, to one ofthe terminating pieces, for example the A end plate or the B end plate,and can be inserted therein.

The stator and the rotor can be arranged in a first axial section of thehousing, and the at least one heat sink can be arranged or inserted intoa second axial section, different from the first axial section, insidethe housing, by virtue of the fact that the heat sink is pushed, forexample, from one side of the housing into the housing and issubsequently screwed thereto.

The motor system can also have an intermediate element which is athermal insulator (poor conductor of heat), wherein the intermediateelement is arranged in the axial direction between the first axialsection and the second axial section. The intermediate element can becomposed, for example, from plastic. The intermediate element isconnected between the two axial sections. For example, the intermediateelement provides a continuous (stepless) junction for the coolantflowing in the axial direction. The intermediate element can have otherfunctional regions which are seal-forming with respect to the adjacentaxial regions, for example in the form of an annular groove for holdingan elastomer seal.

The heat sink can be embodied in an annular shape, wherein the contactfaces of the heat sink are arranged on an inner side of the ring, andthe heat-dissipating regions of the heat sink are arranged as surfaceenlarging structured regions, in particular axially extending coolingfins or cooling webs, on an outer side of the ring.

The heat sink can be formed from a number (for example two) of annularsegments. The annular segments can be formed, for example, as halfshells.

The housing can have a first, central (inner), axially extending duct,wherein the stator and the rotor are arranged inside the first duct. Thefirst duct can be a (circular) cylindrical duct. The first duct can besegmented axially into a number of partial ducts which can be thermallyinsulated from one another, for example, by means of thermal barrierlayers. The housing can also have a number (for example four) of second,in particular cylindrical, axially extending ducts, wherein the secondducts surround the outside of the first duct radially, partially orcompletely, and wherein the second ducts form closed ducts for, inparticular axially, conducting the coolant. In other words, the secondducts surround the first duct on the outside. The second ducts areconnected, in particular in a heat-conducting fashion, to the outer wallof the first duct, for example by virtue of the fact that the first ductand the second ducts have to a certain extent common wall sections. Thesecond ducts form closed, axially extending ducts for conducting thecoolant, in particular in the form of cooling air. Cooling air can beblown into the ducts, for example from the outside, for example by meansof a fan.

The second ducts for conducting the coolant can be continued in theend-side terminating pieces, for example the A end plate and/or the Bend plate, or, for example in the case of air cooling, can conduct thecoolant to the outside and therefore discharge it into the surroundings.A fan can be provided on the A side or on the B side, which fan forcesair as the coolant through the second ducts or draws air therefrom,wherein on the side lying opposite the fan the air escapes again fromthe corresponding terminating pieces or is sucked in through the latter.

The first duct and the second ducts can extend only (exclusively) overthe first axial section of the housing. For this purpose, the housingcan be reworked, with the result that only one housing outer wallremains in the second axial section and the heat sink is plugged intosaid housing outer wall.

The housing can be manufactured by processing, for example milling,sawing, etc., one or more extruded sections or may be an extrudedsection. The heat sink can be manufactured, for example, by means ofaluminum diecasting.

A (radial) cross-sectional area of the heat sink can constitute aregular polygon in its base shape. Owing to the regular polygon, theplanar contact faces, with which the corresponding contact faces of thepower modules can easily be placed in heat-conducting contact, areformed on the inner side of the heat sink.

According to the invention, the power modules which have a(macroscopically) planar contact face or bearing face for thedissipation of heat, are integrated in a thermally optimized fashioninto a housing whose customary configuration does not have any(macroscopic) planar surfaces in its interior.

For this purpose, for example a base shape of the housing can bemodified. For example the housing can be configured in the shape of aninwardly axially continuous polygon. Alternatively, in the interior ofthe housing just one defined axial section can be reworked in such a waythat this axial section is configured in the shape of a polygon. Forthis purpose, for example a polygon can be milled into the interior ofthe housing.

In addition, pockets with (a planar) bearing face for the power modulescan be provided in the inner wall of the housing, wherein the pockets donot completely penetrate the inner wall of the housing, i.e. are closedin the direction of the outer wall of the housing. Alternatively,continuous pockets (windows) can be provided in the housing wall incombination with additional heat sinks which can be plugged through thepockets, wherein the heat sinks have the planar bearing faces for thepower modules. These heat sinks can have elements for increasing thesize of the area around which the coolant flows, which elements projectout of the base shape or into ducts for conducting the coolant of thehousing, with the result that they do not project out of the housing.The elements can be, for example, cooling fins or hedgehog structures.

By means of the invention, the power modules can be coupled to thecoolant satisfactorily in terms of thermal considerations (in thiscontext the power module with the worst coupling is decisive) (Rth assmall as possible), i.e. even a low temperature difference is sufficientto dissipate all the heat loss into the coolant. The active part withthe rotor and stator of the machine and the power modules are thermallyuncoupled, i.e. the capability to transport away heat between the activepart and the power modules is restricted. Furthermore, a sufficientlyhigh protection class (IP 54 or higher) is conceivable, said protectionclass permitting use in industrial environments, vehicles or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail below with reference to thedrawings, in which:

FIG. 1 shows a motor system according to the invention in a perspectiveillustration,

FIG. 2 shows a housing of the motor system according to the invention inwhich a rotor, a stator and a motor shaft are arranged,

FIG. 3 shows a heat sink and power modules which are connected in aheat-conducting fashion to the heat sink,

FIG. 4 shows an axial arrangement of the stator, of an intermediateelement and of the heat sink inside the housing,

FIG. 5 shows the empty housing in a perspective front view, and

FIG. 6 shows the housing with the heat sink inserted.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a motor system 1 according to the invention in aperspective illustration. The motor system 1 has a housing 5 in which arotor 3 and a stator 2 are arranged (see FIG. 2). The rotor 3 isconnected in a rotationally fixed fashion to a motor shaft 14. The motorshaft defines a radial direction and an axial direction of the motorsystem 1. The axial direction is that direction in which the rotationalaxis of the motor shaft 14 extends, and the radial direction is thedirection radially with respect to the rotational axis of the motorshaft 14.

The motor system 1 can be embodied as a PM synchronous machine withintegrated power electronics and closed-loop control electronics.

With respect to FIG. 3, the motor system 1 has ten power modules 4 whicheach conventionally have planar contact faces for dissipating heat. Inthis respect, reference may also be made to the relevant specialistliterature.

The motor system 1 also has an annular heat sink 6 which is composed oftwo, in particular single-piece half shells 6 a and 6 b. The heat sink 6has a cross-sectional area in the form of a regular polygon with tenplanar contact faces 7 which are connected in a heat-conducting fashionto respectively corresponding contact faces of the power modules 4. Forthis purpose, one contact face lies directly on a contact face, wherein,if appropriate, a thermally conductive paste can also be applied betweenthe contact faces which are in contact. The power modules 4 can bepressed onto the contact faces 7 using means (not illustrated).

The heat sink 6 has on the outside regions in the form of cooling fins 8for dissipating heat, wherein a coolant in the form of air flows aroundthe cooling fins 8 in order to dissipate heat.

The motor system 1 also has a control device (not illustrated) which isdesigned to actuate the power modules 4 and to control the operation ofthe motor system 1.

The heat sink 6 is embodied separately from the housing 5, wherein theheat sink 6 is inserted into the housing 5 and is mechanically connectedto it, for example screwed, (see also FIG. 6).

FIG. 4 shows an axial arrangement of the stator 2, an axially connectingintermediate element 11 and the heat sink 6 within the housing 5,wherein the housing 5 is omitted for the sake of clarity.

The stator 2 and the rotor 3 are arranged in a first axial section 9 ofthe housing 5, and the heat sink 6 is arranged in a second axial section10, different from the first axial section 9, inside the housing 5,axially adjacent to an end plate 17 (see FIG. 1). The thermallyinsulating intermediate element 11 is arranged between the first axialsection 9 and the second axial section 11 and serves, inter alia, toconduct the cooling air axially.

Referring to FIG. 5, the housing 5 has a first, axially extending,central, circular-cylindrical duct 12, wherein axially running coolingfins are arranged on an outer surface of the first duct 12. The stator 2and the rotor 3 are arranged within this first duct 12, wherein the duct12 can be closed off with end-side terminating elements, with the resultthat a (closed) chamber for holding the active part composed of therotor and the stator is formed with the heat sink, as a result of whicha high protection class (IP) can be achieved.

The housing 5 also has four axially running second ducts 13, wherein thesecond ducts 13 radially or externally surround the first duct 12, andwherein the second ducts 13 form closed ducts for axially conducting thecoolant. The closed ducts 13 are separated from the surroundings by anouter wall 5 a of the housing 5. The first duct 12 and the second ducts13 extend only over the first axial section 9 of the housing 5, with theresult that in the second axial section 10 only the outer wall 5 a ofthe housing 5 is provided as a jacket or “remains standing” aftermaterial-removing processing, for example milling.

In the second axial section 10 of the housing 5, the heat sink 6 isinserted as an inlay together with the power modules 4 which areconnected to the heat sink, and is subsequently screwed to the housing5. The heat sink 6 can be inserted between the active part and the B endplate into the housing 5. The heat sink 6 can have a sealing face in thedirection of the A end plate, and in the direction of the B end plate itcan have a recess for holding the B end plate, with the result that itis also sealed thereto. Alternatively, the heat sink 6 can be insertedinto the housing 5 between the A end plate and the active part (rotatedembodiment).

The cooling face which is produced by the provision of fins for eachpower module is given approximately the same dimensions. Given a uniformincoming flow, the same thermal resistance will therefore be producedbetween the power module 4 and the coolant for all the installed powermodules. During operation, the same average temperature is obtaineddepending on the power module. In order to forcibly conduct the coolingmedium to the surface-enlarging structures, expulsion bodies can beintroduced into the ducts 13 at suitable locations.

Electrical contact is made with the power modules, for example with thecontrol unit, by means of plug-type connectors 16 which engage incorresponding sockets (not illustrated).

The coolant flows directly axially over the cooling fins 8 of the inlayheat sink 6. The housing 5 is composed, for example, of an aluminumalloy. The heat sink 6 is composed of a material which is a goodconductor of heat, for example copper.

Contact faces of the heat sink 6 with the housing 5 are avoided as faras possible. The mechanical securement of the heat sink 6 in the housing5 is made at a location which is sufficiently far in the axial directionfrom the active part (stator and rotor) of the machine. The contactfaces can be embodied as seal-forming faces. There can be a gap presentbetween the heat sink 6 and the housing 5. This gap can be closed offwith a sealing compound or a seal. The sealing compound/seal is a poorconductor of heat. As a result, further thermal decoupling of the heatsink from the active part is achieved. At the same time, mechanicalstresses (as a result of different degrees of heating of the heat sinkand housing) in the gap which is filled with sealing compound arecompensated.

The cooling fins 8 and the means of guiding the flow of the coolant areconfigured in such a way that the thermal resistance between therespective power module 4 and the coolant is approximately the same. Thecoolant preferably firstly flows over the cooling fins 8 of the heatsink 6 before it is guided past the active part of the machines, i.e.flows through the ducts 13 and effects deheating of the active part.

The heat sink 6 can form a seal with the interior space in which theactive part and the power electronics are arranged. The heat sink 6itself can be impermeable to coolants, for example air.

In the housings without closed cooling ducts 13, “windows” can be cutinto the housing. The heat sinks are, for example, plugged through thesewindows. As a result, they dissipate the heat directly to theenvironmental air. In this context, the heat sink forms a seal againstthe housing on the inside with seals.

The housing can be embodied in two parts. Both housing parts can havethe same external dimensions. The active part of the machine is arrangedin one housing part, and the power modules and the control unit can bearranged in the other housing part. Both housing parts are mounted, forexample, between the end plates. In order to provide thermal decoupling,an intermediate element, which is composed of a plastic which is a poorconductor of heat, can be arranged between them.

In the event of the central duct 12 extending over the entire axiallength of the housing 5, the heat sink can be plugged into the coolingducts 13 from the interior space of the duct 12 via cut-out “windows” inthe outer wall of the duct 12.

The B end plate can be pulled very far forward. The heat sink is thennot plugged through the housing but rather through the side walls of theB end plate. The heat sink is then located behind the recess of the Bend plate and housing when viewed in the axial direction.

There is also the possibility of not plugging the heat sink through thehousing from the inside to the outside but rather conversely from theoutside to the inside. In this embodiment, the sealing faces between theheat sink and the housing are not located on the inside of the housingbut rather on the outside (“reverse plug-in design”).

In a highly integrated drive with just one power module, the entire heatsink can be embodied in one piece. The heat sink can advantageously beplugged in in a completely mounted form (power module with gateactivation and intermediate circuit capacitor) into the machine housingfrom the outside. The formation of contact with the active part takesplace here “blind” by means of plug-type contacts.

The coolant can be water, air, oil or some other suitable material.

What is claimed is:
 1. A motor system, comprising: a stator; a rotor; anumber of power modules which each have planar contact faces fordissipating heat; a control device which is designed to actuate thepower modules; a housing, wherein the stator and the rotor are arrangedinside the housing; at least one heat sink, and a thermally insulatingintermediate element, wherein the at least one heat sink has a number ofplanar contact faces which are connected in a thermally conductivefashion to respectively corresponding contact faces of the powermodules, the at least one heat sink has regions for dissipating heat,wherein a coolant flows around the regions in order to dissipate heat,the stator and the rotor are arranged in a first axial section of thehousing, the at least one heat sink is arranged in a second axialsection, different from the first axial section, inside the housing, thehousing comprises: a first central duct, wherein the stator and therotor are arranged inside the first central duct; a number of secondducts, wherein the second ducts surround the first duct, and the secondducts form closed ducts for conducting the coolant, and the first ductand the second ducts extend only over the first axial section of thehousing, wherein the thermally insulating intermediate element isarranged between the first axial section and the second axial section,and the heat sink is inserted into the housing between the stator andthe rotor and an end plate of the motor system axially adjacent to theat least one heat sink.
 2. The motor system as claimed in claim 1,wherein the at least one heat sink is embodied separately from thehousing, and the heat sink is mechanically coupled to the housing. 3.The motor system as claimed in claim 1, wherein the heat sink is formedfrom a number of annular segments.
 4. The motor system as claimed inclaim 1 wherein the housing is manufactured by processing an extrudedsection.
 5. The motor system as claimed in claim 1, wherein across-sectional area of the heat sink constitutes a regular polygon. 6.The motor system as claimed in claim 1, wherein the heat sink isembodied in an annular shape, the contact faces of the heat sink arearranged on an inner side of the ring, and the regions for dissipatingheat, of the heat sink, are arranged as regions, structured so as toenlarge the surface on an outer side of the ring.
 7. The motor system asclaimed in claim 6, wherein the regions structured so as to enlarge thesurface on an outer side of the ring are structured as cooling fins.